Glacier changes in the Chhombo Chhu Watershed of the Tista basin between 1975 and 2018, the Sikkim Himalaya, India

[摘要] Glaciers of the Tista basin represent an important water source for mountain communities and a large population downstream. The article presents observable changes in the Chhombo Chhu Watershed (CCW) glacier area of the Tista basin, the Sikkim Himalaya. The CCW contains 74 glaciers ( >  0.02 km 2 ) with a mean glacier size of 0.61 km 2 . We determined changes in glaciers from the declassified Hexagon Keyhole-9 (KH-9) (1975), Landsat 5 Thematic Mapper (TM) (1989), Landsat 7 Enhanced Thematic Mapper Plus (ETM + ) (2000), Landsat 5 TM (2010), and Sentinel-2A (2018) images. The total glacier area in 1975 was 62.6  ±  0.7 km 2 ; and by 2018, the area had decreased to 44.8  ±  1.5 km 2 , an area loss of 17.9  ±  1.7 km 2 (0.42  ±  0.04 km 2  a −1 ). Clean glaciers exhibited more area loss of 11.8  ±  1.2 km 2 (0.27  ±  0.03 km 2  a −1 ) than partially debris-covered and maximally debris-covered glaciers. The area loss is 5.0  ±  0.4 km 2 (0.12  ±  0.01 km 2  a −1 ) for partially covered glaciers and 1.0  ±  0.1 km 2 ( −0.02   ±  0.002 km 2  a −1 ) for maximally covered glaciers. The glacier area loss in the CCW of the Sikkim Himalaya is 0.62  ±  0.5 km 2  a −1 during 2000–2010, and it is 0.77  ±  0.6 km 2  a −1 during 2010–2018. Field investigations of selected glaciers and climatic records also support the glacier recession in the CCW due to a significant increase in temperature (0.25  ∘ C a −1 ) and more or less static precipitation since 1995. The dataset is now available from the Zenodo web portal: https://doi.org/10.5281/zenodo.4457183 (Chowdhury et al., 2021).

[学科分类] 眼科学